STUDY OF ORE LIFTING EFFICIENCY USING MIXTURE OF BENTONITE SUSPENSION AND SAND FOR DEEP SEA MINING

Abstract

 To lift up coarse and heavy ores from deep seafloor, a method by using carrier material (mixture of viscous fluid and fine particles, CM) was proposed. However, appropriate mixing proportions of CMs have not been studied yet. Bentonite suspension is one of the candidate viscous fluids since it is widely used as drilling fluid for removing cuttings. Thus, this study focused on ore lifting efficiency of CMs of mixture of water, bentonite and sand particles.

 Firstly, rheological characteristics of CMs were measured. The results of measurements demonstrated that CMs can be assumed as Bingham fluid. Then, a series of model tests of ore lifting were conducted using CMs of various mixing proportions of water, bentonite and sand particles. The test results showed that heavier and larger ores were lifted using CMs than by the conventional lifting method in which crushed ores were pumped up with sea water. Moreover, the yield stress of CMs was found to enhance ore lifting efficiency if CMs can be assumed as Bingham fluid.